High-bay stores for storing a unit load in a compressed manner, wherein the unit load is mounted on pallets, are used in a multiplicity of widely varying geometries and generally have a plurality of racks which are preferably erected in rows and in which the unit load can be stored or retrieved. High-bay stores of this type are often operated with regard to storage and retrieval by means of forklift trucks, wherein the forklift trucks move in the passages between the rows formed by the racks. Storage systems of this type are not optimal with regard to the economic use thereof. Automation of high-bay stores of this type is therefore sought using loading and unloading systems which reliably permit supply or retrieval of a unit load to or from predefined storage spaces within the rack apparatus.
In DE 10 2010 005 591 A1 is a high-bay store for storing pallets, comprising a plurality of high racks described which are erected in rack aisles, and therefore passages are produced between the rack aisles, wherein storage channels in which at least one pallet can be stored are formed in the high racks, wherein use is made of what is referred to as a tandem shuttle which comprises a passage truck and a channel truck, wherein the passage truck is designed for travel on a passage rail region and the channel truck is designed for travel on a channel rail region. The channel truck is designed for transport of a pallet in a channel rail region, and the passage truck is designed for transport of the channel truck in a passage rail region. In addition, use is made of a vertical transport device which permits transport of the tandem shuttle from a first plane onto a second plane.
A similar solution is in DE 32 07 860 A1 described which relates to a conveyor device for a warehouse system, with high racks erected in rows. A low-height truck which carries a carrier truck in piggyback fashion can be moved between the rows in order to fetch a unit load from the respective racks. The low-height truck can be moved here together with the carrier truck and the unit load in an elevator in order to be transported by the latter between the floors and a transfer station.
As closest prior art, DE 1 556 071 A1 describes a mechanized pallet rack store with a rack structure, into the pallet channels of which, which are provided with pallet support consoles and travel rails, optionally mechanized lift trucks can be moved over the entire length, said pallet rack store having transverse travel tracks floor by floor, at the end of which elevators open, in which the lift trucks can be transported in the vertical direction. The lift truck itself has two traveling mechanisms for the x direction and z direction. There is a travel drive assembly for each direction. Furthermore, there is a lift drive assembly for raising and lowering the traveling mechanisms for a change of direction. The change of direction is undertaken here in such a manner that the lift truck carries out a lifting/lowering movement of the traveling mechanisms, wherein, during this operation, the pallet pickup unit also has to be raised or lowered. This requires a relatively high energy expenditure since, for the change of direction, the weight of the pallet pickup unit, and therefore also the pallet mounted on the pallet pickup unit, has to be raised or lowered. The approach dimension is also changed because of the additional lift.
WO 2005/077789 A1 discloses an automated warehouse rack store comprising pallet transport apparatuses which are arranged so as to be movable in the x and y direction within the warehouse. In this case, there is a set of wheels for each direction (x, z). The drive of the various sets of wheels is controlled here via two couplings. The shuttle has three configurations, namely the travel in the passage direction, the travel in the pallet direction and the lifting in the pallet direction. Transverse movements in the z direction are possible only on special passages. A complete, variable movement on the plane in the x and z direction is not possible. The straight-ahead movement is not controlled; on the contrary, use is made of lateral guide rollers and rails which are intended to keep the shuttle in the track thereof. The drive and movement means for the travel in the longitudinal and transverse direction x, z can be activated separately here.
U.S. Pat. No. 3,978,995 A discloses a storage installation with a pallet shuttle which permits only travel in the x direction, in which a mechanism lifts the pallets from the rack, a change of direction is not possible and only single-depth storage within the rack system is possible.
EP 2 308 778 A2 and EP 2 308 777 B1 disclose an automatic storage shuttle of the type mentioned at the beginning, with an upper carrier surface which can carry a loading unit, a lifting device in order to raise/lower the upper carrier surface, four wheel arrangements which are arranged in each case in the corner region of the shuttle and are drivable individually, in each case via a drive assembly. The wheels are present so as to be rotatable through 90°, and therefore a change of direction is possible. All four wheels are in each case driven individually via a corresponding drive assembly. Sensors present on the drive wheels detect the respective wall distance to the surrounding components. The rotational speed or the torque of the driven wheels is regulated via a control device depending on received signals. The movement of the shuttle is possible in two vertical directions by rotation of the wheel arrangements through 90°.
JP 08157016 A discloses a pallet shuttle in which wheel units are in each case arranged in the corner region, the wheel units having a dedicated drive assembly and being rotatable in the driving direction thereof in the x or z direction as required. The pallet pickup unit can be raised or lowered via a special mechanism.